Here we have brass on the left and aluminum case ammo on right. The choices between aluminum and brass case ammo largely depends upon availability, price and your application. Billions of rounds have been produced with brass cases. Aluminum cases appeared in the 1980’s. Aluminum case ammo to the best of the authors knowledge has only been manufactured for pistol ammo. The presumed reason for pistol ammo only is chamber pressure. Center fire rifle case pressures can go as high as 55,000 PSI or higher in some cases. The 9X19mm pistol ammo shown have a rather high pressure of 35,000 PSI. Aluminum case ammo is available in 9X19mm (Luger), .380ACP, .40 S&W, .38 SPL. .45ACP to name a few.
The alloy for brass cartridge cases is about 70% copper and 30% zinc. Some brass alloys can be around 60% copper, 36% zinc possibly with a little tin & iron. So Brass alloys vary according to the application. It is a normal assumption cartridge case alloys will vary somewhat from one manufacturer to the next. Each factory takes due care in every step of production to assure close tolerances and hardness found at various points on their case.
The manufacturers producing aluminum case ammo state it is made from “Aircraft Alloy”. Some common alloys are 1060, 1100, 3003, 5052, 5083, 6061, 6082, & 7075. Pure aluminum is 1000 Series and is far too soft for any structural application, let alone cartridge cases. The strongest aircraft aluminum is 7075T6511 this is used for aircraft structural parts with a yield strength of 72,000 PSI. Another common aircraft grade is 2024T3511 with a yield strength of 46,000 PSI. So as can be seen “Aircraft Alloy” includes several alloys. Each manufacturer will undoubtedly choose the alloy which forms best for production and offers sufficient strength.
Brass cases are normally made with Boxer primer pockets with the flash hole in the center of the primer pocket. Boxer primers have the anvil as a part of the primer. Many reload and fire cycles are possible before the brass case wears out. Annealing brass case necks helps extend case life dramatically. Annealing is easily performed with the Anneal-Rite unit covered later.
Thus far to date all aluminum cases found have had Berdan Primers. These cases have two flash holes located off center and can’t be de-primed using conventional reloading dies. They can be re-primed by removing the spent Berdan primers with a sharp pointed tool, piercing the primer at an angle and prying it out. From a practical viewpoint most shooters firing Berdan primed cases don’t bother to collect them for reloading.
Pros and Cons of Aluminum Case Ammo
Aluminum case ammo has proved reliable and a good choice to attain proficient marksmanship. Generally, the more trigger time a person has the more proficient they become. Like all sports to excel requires practice. The primary benefit of aluminum case ammo is price savings. If you’re an occasional shooter burning a box or two a year the savings currently is just $1.00 to $3.00 per box of 50. On the other hand, if shooting a case or more per year, not reloading, aluminum cased ammo will add up allowing more bang for the buck. Even if you aren’t a volume shooter you may want to lay in a case or more for peace of mind and security. Store ammo properly is important and is covered in another post.
The choice between aluminum or brass case ammo should include several considerations. First is it manufactured by a reliable US firm. This assures a reasonable level of quality and safety. A few very bad issues with some foreign ammo have been encountered. An over charged load can destroy a firearm and or render severe injury to the user. One firearm manufacture states if a certain brand of foreign ammo is used it voids their warranty.
Those reloading ammo can improve the performance of cases through annealing the case neck. Brass case neck annealing will increase accuracy and extend case life. Annealing can be successfully performed on the very small 9mm Luger cases and is beneficial for pistol & rifle cases and all up to and including the huge 20mm Vulcan case. A practical affordable annealer is available at www.cartridgeanneal.com there is a good video showing this in operation. If questions call 479-629-5566 9am to 9pm central time Mon-Sat.
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